Increased serum sulfate in pregnancy: relationship to gestational age.

Controlled-flow ion chromatography has significantly improved the precision with which inorganic sulfate (SO4) can be measured in serum. In this study, we have shown that serum SO4 is increased in pregnancy. The increase appears to follow gestational age, resulting in a 39% higher value by the middle of the third trimester. We suggest that this increase is a natural physiological process, which enhances SO4 availability to the growing fetus and placenta.